Apparatus for forming sheet metal



June 24, 1969 K. 1.. MILTENBERGER 3,451.,247

APPARATUS FOR FORMING SHEET METAL Sheet of 8 Filed April 12, 1967 BY I ZJune 1969 K. L. MILTENBERGER APPARATUS FOR FORMING SHEET METAL Sheet 2of 8 Filed April 12, 1967 I N V E NTOR. Mmvazzazz BY 2 Z I I Afidi/VE/June 24, 1969 1.. MILTENBERGER 3,451,247

APPARATUS FOR FORMING SHEET METAL Sheet Filed April 12, 1967 June24,1969 K. I... MILTENBERGER 3,451,247

APPARATUS FOR FORMING SHEET METAL Filed April 12, 1967 Sheet 4 of 8 a 7g6% m0 /0 /20 ma My 1 1 g. Z- I f r w/25 m 77azA/0 June 24, 1969 K. 1..MILTENBERGER I 3,451,247

APPARATUS FOR FORMING SHEET METAL Filed April 12, 1967 Sheet 5 of sArramvzfl June 24, 1969 K, 1.. MILTENBERGER 3,451,247

APPARATUS FOR FORMING SHEET METAL Sheet Filed April 12, 1967 i\ mw Qxmwv June 1969 K. MILTENBERGER 3,451,247

APPARATUS FOR FORMING SHEET METAL Filed April 12, 1967 Sheet 3 of 8 gya27/ 274 25 ass-2% 27J a 270 772 252 I NVENTOR. ,m z/ ZMm/Jaae UnitedStates Patent 3,451,247 APPARATUS FOR FORMING SHEET METAL Kenneth L.Miltenberger, Lakewood, Calif., assignor, by

mesne assignments, to McDonnell Douglas Corporation, Santa Monica,Calif., a corporation of Maryland Filed Apr. 12, 1967, Ser. No. 630,452Int. Cl. B21d 45/00, 43/ 18, 43/00 US. Cl. 72346 12 Claims ABSTRACT OFTHE DISCLOSURE Background of the invention This invention lies in thefield of hydraulic sheet metal forming presses and deals withimprovements in efficiently delivering workpieces to the forming zone ofa press and removing them therefrom. It is directed particularly to thecombination of a hydraulic forming press with a reload station for theexchange of blank workpieces for formed workpieces, a conveyor systemfor moving the workpieces to the desired locations, and transfermechanism for handling workpieces at the various locations, and to noveldetails of the various components. The components cooperate to make itpossible to supply workpieces to the press and remove them as rapidly asthe press can be cycled regardless of the nature or complexity of theworkloads.

Various types of presses have been used for producing formed sheet metalparts. When large numbers of identical parts are to be made, a draw typepress with fixed tooling is usually preferred. Such a press is notsuitable for short runs of many different parts. In most cases suchparts are processed in a press having a rigid generally fiat horizontalbed on which one or more form blocks carrying blank workpieces may belaid. A head is located above the bed and carries a large elastomericpad which overlies the bed and is forced toward it to form theworkpieces on the form blocks. The head may be vertically movable byfluid pressure to force the pad toward the bed, or it may have a setposition and the pad may be forced down by a hydraulically expansiblecontainer carried by the head.

Some of the hydraulic presses mentioned above have rather slow operatingcycles and it is possible to keep them supplied with work by the use ofone or two work tables or pallets which may be loaded at leisure andmoved into and out of the press manually or automatically. Some of thenewer versions of these hydraulic presses have very fast operatingcycles, at least one having a cycle of only about twenty seconds. Tomake full use of such a press it is necessary to have a comparativelylarge number of work-holding pallets and workmen to reload them. Toproperly handle these pallets, various conveyor systems have beendevised which are fairly satisfactory but still have drawbacks, such asinsertion of a new pallet being delayed by removal of the previous one,and faster-loading pallets in a series being delayed by slower-loadingpallets.

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Summary of the invention The present invention solves the above problemsand provides a complete metal forming apparatus which can operate asrapidly as the cycle of the press will permit, is efficient in theamount of equipment and floor space needed, and is very convenient inall aspects and very easy to operate. Generally stated, the apparatusincludes a press which has a rigid flat bed and a head which isvertically movable from an open position to a closed positionimmediately over the bed, on which a pallet with form blocks andworkpieces is located. An elastomeric pad carried by the head is forceddown toward the bed by fluid pressure in an expansible container alsocarried by the head. The vertical separating pressure is resisted by apair of clamp rings which move laterally to grip flanges on the marginsof the press bed and head. When the clamp rings are separated laterally,the head is raised and the press is open at two opposite sides.

To speed the replacement of workloads in the press, a loading station isprovided at the front or first side of the press and an unloadingstation is provided at the rear or second side of the press. Transfermechanism at the loading station pushes the pallet which is on the pressbed to discharge it to the unloading station and at the same time pushesthe succeeding pallet from the loading station on to the press bed.Because of this straight through action, the succeeding pallet does nothave to be held in an out of the way place while the previous pallet isbeing removed from the press and dispatched to a reloading area.

A conveyor system has a supply section to deliver reloaded pallets tothe loading station and a return section to receive pallets of processedparts from the unloading station. The delivery end of the return sectionand the receiving end of the supply section are remote from the pressand define an exchange zone, this part of the return section preferablybeing arranged in spaced parallel relation beneath the correspondingpart of the supply section. At the exchange zone there are a pluralityof reload stations, usually varying between two and eight. Each reloadstation includes a reload table where a selected pallet is' locatedtemporarily while a workman removes formed parts from one or more formblocks carried by the pallet and replaces them with blank workpiecesfrom a convenient storage rack.

In order to achieve maximum utilization of the press, a distinct,selected pallet having certain form blocks thereon is assigned to eachworkman and he has a rack of blanks for these form blocks. His selectedpallet is de- 'tected and discharged from the return section of theconveyor system only to his particular reload station and reload table,and as soon as he reloads all of the form blocks with blank workpieceshe may immediately transfer his pallet to the return section of theconveyor system without regard to the rate of progress of any of theother workmen. Since each reload table is independently accessible toboth sections of the conveyor, it is apparent that one workman mayreload a few large form blocks in a half minute while another workmanmay require several minutes to reload a large number of small formblocks, and yet the fast reload is not held back by the slow reload.Also, the order in which the pallets return from the press will notcause any delay. The number of reload stations used at one time may bereadily adjusted to provide an average number of loads per minute justequal to the capacity of the press.

Brief description 0 the drawings Various other advantages and featuresof novelty will become apparent as the description proceeds inconjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a hydraulic metal forming pressparticularly suited for use in the combination of the invention;

FIG. 2 is a perspective view of the complete apparatus of the invention;

FIG. 3 is a schematic plan view of the apparatus of FIG. 2;

FIG. 4 is a schematic view in elevation of part of the apparatus of FIG.3;

FIG. 5 is a schematic end view in elevation of the conveyor system andreload station of FIG. 3;

FIG. 6 is a schematic plan view of the return section of the conveyorsystem at a reload station;

FIG. 7 is a schematic view in elevation of a portion of the returnsection of FIG. 6 with the detection means to identify selected pallets;

FIG. 8 is a schematic side elevational view of the press, loadingstation, and transfer mechanism;

FIG. 9 is a schematic plan view of the apparatus of FIG. 8;

FIG. 10 is a schematic side elevational view of the press and theunloading station and its transfer mechan1sm;

FIG. 11 is a schematic plan view of the apparatus of FIG. 10;

FIG. 12 is a schematic view in side elevation of the transfer mechanismof the unloading station;

FIG. 13 is a schematic plan view of a modified form of the apparatus;and

FIG. 14 is a schematic view in side elevation of a portion of theconveyor system and the roller drive means therefor.

Description of the preferred embodiments A hydraulic press which isparticularly suitable for incorporation in the apparatus of theinvention is illustrated in FIG. 1, and generally comprises a base 10 onwhich is mounted a press bed 12 having a circular plan- =form, themargin 14 overhanging the pedestal 16 to form a flange. A head 18 iscarried by arm 20 which is pivoted at 22 to the base and is raised andlowered by hydraulic servornotors 24. The head includes a rigid backingmember 26 to which is connected a stress ring 28 forming a cavity inwhich is located an elastomeric member 30. Between members 26 and 30 islocated an expansible fluid container including a plate 32 and anelastic diaphragm 34. When the head is in juxtaposition to the pressbed, hydraulic fluid at high pressure is supplied through line 36 todistend diaphragm 34 and force member 30 toward the press bed to applyforming pressure to one or more sheet metal blanks on form blocks whichare lodged on the press bed in known manner. Clamp rings 38 engage theflange portions of the press bed and the head to resist the separatingpressure produced during the forming operation. When they are separatedby hydraulic servo motors 40 as shown in FIG. 1, the press is open atthe front and rear, or opposite sides, making it particularly suitablefor loading and unloading in accordance with the invention.

The press of FIG. 1 is shown in FIGS. 2, 3 and 4 incorporated into theremainder of the apparatus of the invention including a conveyor systemhaving a supply section 42 and a return section 44. The delivery end ofthe supply section is adjacent to loading station 46 and the receivingend of the return section is adjacent to unloading station 48. Theirrespective receiving and delivery ends are remote from the press anddefine an exchange zone 50. At the exchange zone are two or more reloadstations 52, 54, each having a reload table 56, 58. Pallets 60, in theform of disks, travel from the reload stations to the loading station 46on conveyor supply section 42 on rollers 62, at least some of which aredriven by contact with one or more belts 64 in a manner to be describedlater. Preferably at least two sections 66 and 68 of the rollers areindependently actuated in order that they may remain stationary andaccumulate pallets for the loading station while other rollers continueto rotate.

After processing, pallets 60 are discharged to unloading station 48which transfers them to the gravity portion of return section 44. Whenthey reach the horizontal portion of section 44 they are conveyed bylive rollers until they reach their appropriate reload stations 52 or54. They are then transferred by means later described to elevatorsections 70 or 72 and thence to reload tables 56 or 58 where the formedparts are removed and replaced by new blanks. The sequence is completedby transporting the reloaded pallets across transport sections 74 or 76to section 42 for return to the loading station.

A power unit 78 supplies hydraulic fluid at high pressure to operate thepress and compressed air for various servo motors throughout theapparatus. An electrical console 80 is provided to supply power whereneeded and to directly control various operations which are notautomatically actuated. Electrical conduits 82, 84, 86 and 88 extendfrom the console respectively to the power unit, unloading station,loading station, and bus 90 which provides electric power for variousoperations along the conveyor system.

It is, of course, essential that each pallet return to its originalreload station because the necessary blanks for reloading the pallet areavailable only to the workman at that station. Therefore, each pallethas a distinctive index formation for cooperation with detection means.As previously noted, all of the pallets are in the form of disks andthey are all of the same diameter which is substantially the same as thewidth of the conveyor sections between side rails so that the disks atall times during their travel will be located with their centers on thecenter line of the conveyor section. Each pallet is provided on itsbottom or lower side with a concentric annular groove 92 which may beabout an inch wide and an eighth to a quarter inch deep. All of thepallets belonging to one station have a groove of the same radius, whichis measurably diiferent from the radius of the groove in any otherpallet. Since the pallets presently being used are 39 inches in diameterthe radii of the grooves may differ by several inches if desired.

As will be seen by reference to FIGS. 6 and 7, the detection andidentification means comprise a pair of switch actuators 94 and 96adjacent to each reload station, provided with sensors 98 and 100. Theactuators are pivoted to the conveyor structure at 102 and 104 and theirlower ends are adapted to contact switches 106 and 108. They areprovided with load springs 110 and 112 and stops 114 and 116 so thatthey are biased to an inoperative position in which the tips of thesensors lie slightly above the upper plane of rollers 118. It will beseen in FIG. 6 that sensor 98 is located laterally of the center line ofthe conveyor a distance equal to the radius of groove 92 and that sensoris on the center line of the conveyor and onward of sensor 98 a distanceequal to the radius of the pallet.

With this arrangement, as viewed in FIG. 6, pallet 60 approaches fromthe left. When its leading edge reaches sensor 98, it depresses it tothe extent necessary for the sensor to pass under the bottom of thepallet. This motion is sutficient to cause the lower end of actuator '94to contact switch 106 and pass beyond it to the dotted line position. Asthe pallet advances, sensor 98 will enter groove 92 and the lower end ofthe actuator will close switch 106. Since the relative movement of thesensor is along a tangent of the groove and the sensor is considerablynarrower than the groove, the switch will remain closed during severalinches of travel of the pallet. The sensor 98 will still be in thegroove when sensor 100 is depressed by the leading edge of the pallet,closing switch 108 and cornpleting a series circuit through the twoswitches by way of conductor 120.

The circuit is completed through conductors 122 and 124 and a powersource, to an actuator 126, FIG. 5, which supplies compressed air toservomotor 128. Roller track assembly 130 is pivotally mounted to thestructure at 132 and is pivotally connected at 134 to the piston rod 136of the servo motor. In inoperative position the assembly lies just belowthe upper plane of rollers 118. When the servo motor is actuated, itraises the left end of the assembly, as viewed in FIG. 5, and the entireassembly rises above the roller plane at an angle, picks up the pallet,and transfers it to the reload station.

As will be apparent from FIG. 6, pallet 138 passes the first reloadstation without triggering its roller track assembly because groove 140is of smaller radius and sensor 98 does not enter the groove. Sensor 142however will enter groove 140 and Will act with sensor 144 to cause thetransfer of pallet 138 into the second reload station. If the positionsof the two sets of sensors were reversed they would still reactcorrectly because the sensor closer to the center line would enter andleave the larger radius groove at times when its cooperating sensor wasnot depressed.

Returning to FIG. 5, when the pallet 60 is discharged to its reloadstation it rolls onto elevator section 72 and its leading edge contactsswitch 146. This action triggers actuator 148 which delivers compressedair to servo motor 150 which raises elevator section 72, guided by guiderods 152, to the level of the supply conveyor, and the pallet is thenrolled onto reload table 58. The workman then removes the formed partsfrom the form blocks and replaces them with blanks and moves thereloaded pallet across transport section 76 onto the supply conveyorsectlon for return to the press.

The loading station and its transfer mechanlsm are illustrated in FIGS.8 and 9, in which extension 154 of base carries a plurality of guides156. Platform 158 is provided with guide rods 160 which are mounted forsliding movement in guides 156, and the platform 1s movable from itssolid line position forward to the dotted line position adjacent to thepress bed 12 by servomotor 159. The platform carries a plurality of balltransfer rollers 161 to facilitate movement of pallets 60 onto theplatform from the supply section of the conveyor and then laterally ontothe press bed.

A support plate 162 is mounted on platform 158 by standards 164 andcarries depending guides 166 near 1ts forward end and depending bosses168 near its rear end. Tubular guide rods 170 are slidingly mounted inguides 166 and telescope over interior guide rods 172 anchored in bosses168. Guide rods 170 carry pusher foot 174 at their rear end and bar 176at their forward end, the bar in turn pivotally carrying pusher foot178. The bar 1s moved fore and aft by servo motor 180. Bar 176 isprovided with a central boss 182 and side stop members 184. Pusher foot178 is provided with a pair of rearwardly extending ears 186 which spanboss 1'82 and are connected thereto by pivot pin 188. Clevis 190 isrigidly mounted on foot 178 and pivotally connected at 192 to piston rod194 of servo motor 196. The latter is pivotally mounted on bar 176 byclevis 198. Operation of servo motor 196 swings foot 178 upwardly aboutpivot pin 188 to a sufiicient extent to clear a form block and itsworkpiece resting on a pallet.

The operation of the transfer mechanism takes place in two stages. Inthe first stage, servo motor 159 is actuated to move platform 158together with all the elements mounted thereon forward toward the pressuntil the forward edge of the platform is in juxtaposition with the nearedge of the press bed as indicated by dotted lines in FIGS. 8 and 9. Itwill be seen that at this time the pallet to be loaded actually overliesthe edge of the press bed and pusher foot 178 is very close to thepallet to be discharged. Servo motor 180 is now actuated and pressurefeet 174 and 178 move forward with respect to the platform. As indicatedin FIG. 9 in dotted lines, foot 178 moves almost entirely across thepress bed and pushes the posit the succeeding pallet concentrically onthe press be The pusher feet are now tron with respect to the of theretraction retracted to their original posiplatform, but at thebeginning movement servomotor 196 is actuated to swing foot 178 upwardlyso that it will pass back over the form block and workpiece now on thepress bed without interference. When this step of retraction iscompleted, the platform itself is retracted to its original positionshown in solid lines and is ready to receive the next pallet from thesupply section of the conveyor.

The construction and operation of the unloading station areschematically depicted in FIGS. 10, 11 and 12. Transfer means to shift adischarged pallet to the receiving end of the return section of theconveyor system takes the form of a pair of side plates 200, 202 securedin verti cal spaced parallelism to structural members 204, 206 rlgidlyattached to base 10. The side plates extend perpendicular to thedirection of movement of the pallets received from the press and carrybetween them a belt 208 mounted on a series of pulleys arranged toprovide a belt conveyor surface elevated slightly above the edges of theside plates and actuated to transfer pallets laterally of theirdirection of movement from the press bed to the un loading station.

Pulleys 210, 212 and 214 extend between side plates 200 and 202 and, asbest seen in FIG. 12, support the belt in a horizontal plane to receiveand move a pallet in the desired direction. Pulleys 216 likewise extendbetween the side plates 200 and 202, and the belt is so threaded overall of the pulleys as to provide two deep depressions or troughs 218,and the side plates are out way at 220 to provide clearance for theroller track means which receives the pallets from the press. Pulley 210is driven by motor 211 by means of a chain drive.

The roller track means comprises two track sections 222 connected toeach other, as in FIG. 11, by cross braces 224 and 226, each tracksection carrying a plurality of rollers 228. In FIG. 12 and in the solidline position of FIG. 10 the roller tracks are in retracted position andtheir rollers lie below the plane of the belt. Referring particularly toFIG. 10, it will be seen that the left, or remote, ends of track section222 have depending side plates 229, each carrying a support roller 230and a safety roller 232. The support roller rides on the upper surfaceof track 234, which is in the form of a horizontally extending flange,and the safety roller engages the under surface of track 234 to preventunintentional displacement of the track sections. It will be noted thatthe extreme outer end of track 234 has an inclined upper surface 236 onwhich roller 230 rests when the track section is fully retracted in thesolid line position.

As stated above, when it is fully retracted, the track section ishorizontal and slightly below the level of belt 208. The forward end ofthe track section is pivotally connected at 238 to crank arm 240 whichin turn is pivotal- 1y mounted at 242 on block 244. The lower end of thecrank arm which extends below pivot 242 is pivotally connected to theend of extension 246, which in turn is connected to servomotor 248 bypiston rod 250.

When the time arrives for a pallet 60 to be discharged to the unloadingstation, piston rod 250 is retracted, swinging crank arm 240 clockwise.This movement not only moves the track section forward but also raisesit. At the same time roller 230 at the rear rides up the inclinedportion 236 of track 240 and then moves forward on the horizontalportion. The crank arm produces more rise than the inclined portion 236and consequently the track section is inclined to the left as viewed inFIG. 10, the foremost roller 228 being just level with press bed 12.When pusher foot 178 moves fully forward as previously described itpushes pallet 60 almost entirely ontotrack sections 222 and, since theyare inclined, the

pallet will continue until it strikes stop 252. Piston rod 250 is nowextended, crank arm 240 rotates counterclockwise to the full lineposition, and roller 230 returns to inclined portion 236, causing thetrack section to retract below the belt level. It therefore deposits thepallet on the belt and the latter transfers it to the receiving end ofthe return section of the conveyor.

It is sometimes desirable because of the loading rates of the workpieceson the pallets or because of limitations on floor space or arrangementto extend the conveyor system laterally of the press to each side. Sucha modified arrangement is shown in FIG. 13 which schematically depictsan arrangement similar to that of FIG. 3 but with a second conveyorsystem comprising supply section 254 and return section 256 extendingopposite to sections 42 and 44.

In order to route all of the pallets back to their original reloadstations the detection system of FIGS. 6 and 7 may be used at theunloading station. In one form, belt 208 is replaced by two separatebelts 258 and 260, leaving a clear area extending laterally of thedirection of discharge movement of the pallet from the press and locatedat a distance of half the diameter of the pallet from the stop 262. Aswitch 264 is mounted on stop 262 to be closed by the contact of thepallet leading edge. A pair of sensors 266 and 268, for example, arelocated in the lateral clear space between the belts, each sensor beinglaterally spaced the proper distance to identify a particular selectedpallet. As shown, sensor 266 enters the groove in pallet 60, closing aswitch, not shown, which is in series with switch 264. When the twoswitches are closed simultaneously a circuit is completed through adirectional switch for the belt motor 211, causing it and belts 258 and260 to rotate in a direction to transfer pallet 60 to section 256. If,on the other hand, the groove in pallet 60 were to match sensor 268, thecombination with switch 264 could be used to transfer the pallet tosection 44. Obviously there may be several sensors for transfer in eachdirection.

As mentioned above in connection with FIG. 3, some or all of theconveyor rollers may be live, or driven, and they may be independentlydriven in large or small groups. For example, in FIG. 3, sections 66 and68 of the rollers are desirably independently driven so that they may beheld stationary at will to accumulate several loaded pallets adjacent tothe loading station of the press.

FIG. 14 illustrates in schematic form a roller driving system suitablefor the above purpose. A conveyor structure includes a base 270, endplate 272, and side rail 274 carrying conveyor rollers 276 for rotation.A belt 278 extends horizontally with one pass in proximity to rollers276. It is carried on drive roller 280 and another roller, not shown,and the drive roller is driven by motor 282 through belt 284. Idlerrollers 286 are mounted for rotation on a rail 288 which is providedwith inclined slots 290. Side rail 274 carries pins 292 which engageslots 290 to support rail 288. As the latter is shifted horizontally inopposite directions as indicated by the arrows, it rises and falls,changing the position of rollers 286 with respect to belt 278.

When rail 288 is lowered, belt 278 sags sufiiciently to clear rollers276 and they will remain stationary even if the belt is moving. When itis desired to positively drive rollers 276, rail 288 is moved to theleft which causes it to rise and bring idler rollers 286 into contactwith belt 278. They are actually raised to such a position that the beltcannot pass in a straight horizontal line between rollers 276 and 286.The serpentine path brings the belt into positive driving contact withrollers 276. This system is particularly useful when it is desired touse a long single drive belt and at the same time control several shortsections of rollers independently.

In the system as presented, it is assumed that most phases of thevarious operations are to be controlled by the operator at the mainconsole 80 adjacent to the loading station, or by the reload workmenusing small auxiliary consoles. However, it is apparent that the systemcan be substantially fully automated if desired by the use of snapswitches, limit switches, tape controls, etc.

The use of round pallets and a round press bed is particularlyadvantageous because it obviates the necessity of orienting the palletsat any stage in the operation. The circular planform also makes possiblethe coding formations which have been described. It should be noted thatan important advantage of the system is that two or more pallets may beassigned to each reload station and used in the system at the same timewithout confusion or delay because of the coding arrangement and thefact that pallets can be placed on the supply section at random.

It will be apparent to those skilled in the art that various changes maybe made in the construction and arrangement of parts as disclosedwithout departing from the spirit of the invention, and it is intendedthat all such changes shall be embraced within the scope of thefollowing claims.

I claim:

1. Apparatus for forming sheet metal work-pieces to predeterminedshapes, comprising: a hydraulic press having a rigid bed and a forminghead; said bed being adapted to receive a pallet carrying at least oneform block of predetermined shape with a sheet metal workpiece thereon;said forming head including a rigid backing member and an elastomericmember carried thereby and adapted to be forced by fluid pressure towardsaid bed and pallet to form the workpiece on the form block; said pressbeing open at opposite sides at least on occasion for loading anddischarge of pallets; a loading station at a first side of said pressand an unloading station at the second side of said press; a conveyorsystem including a supply section having a receiving end remote fromsaid press and a delivery end adjacent to said loading station, and areturn section having a delivery end remote from said press and areceiving end adjacent to said unloading station; the receiving end ofthe supply section and the delivery end of the return section beingadjacent to each other and defining an exchange zone; a plurality ofreload tables at said exchange zone, each independently connected tosaid sections to receive selected pallets from the return section anddischarge them to the supply section; means at the exchange zone toidentify and divert selected pallets from the return section to eachreload table; means to transport pallets from each reload table to thesupply section; transfer mechanism at said loading station adapted todischarge a pallet from the press bed to the unloading station and totransfer a succeeding pallet from the loading station to the press bed;and transfer means at the unloading station to forward pallets to theadjacent end of the return section.

2. Apparatus as claimed in claim 1; and, in addition thereto, a secondconveyor system of the same type extending away from the press in asecond direction; and means at the unloading station to identify anddivert selected pallets to each of the return sections of the conveyorsystems.

3. Apparatus as claimed in claim 1; said press bed being circular inplanform; and a plurality of pallets for use in the press; each palletbeing circular in planform to obviate the necessity of orienting it fortravel through the press or throughout the conveyor system.

4. Apparatus as claimed in claim 1; the supply section of the conveyorsystem being provided with load-supporting rollers throughout itslength; at least some of said rollers being power driven to move thepallets from the exchange zone to the loading station; at least onegroup of said rollers at the delivery end being operable independentlyof the others to remain stationary and provide temporary storage forloaded pallets adjacent to the loading station while the other rollersare being driven.

5. Apparatus for sequentially forming a series of sheet metal workpiecesto predetermined shapes, comprising:

a hydraulic press having a rigid bed and a forming head; said bed beingadapted to receive a pallet carrying at least one form block ofpredetermined shape with a sheet metal workpiece thereon; said pressbeing open at opposite sides at least on occasion for loading anddischarge of pallets; a loading station at a first side of said pressand an unloading station at the second side of said press; said loadingstation comprising a platform at the height of the press bed andadjacent thereto and adapted to receive successive loaded pallets fromthe supply section of a conveyor system; and transfer mechanism at saidloading station including a first pusher foot at the edge of saidplatform adjacent to the press bed and a second pusher foot at the edgeof said platform remote from the press bed, said first and second feetbeing adapted to respectively engage the margins of the pallet on thepress bed and the pallet on the platform; and means to move said feet inunison toward the press and over the press bed a sufiicient distance todischarge the pallet from the press bed to the unloading station and todeliver the succeeding pallet from the platform to the press bed.

6. Apparatus as claimed in claim and means to raise the first foot toprovide vertical clearance between it and the succeeding loaded palletduring the return stroke of the transfer mechanism.

7. Apparatus as claimed in claim 5; said loading station furthercomprising a base; said platform being mounted on said base for movementtoward and away from the press; and said pusher feet being mounted onsaid platform for movement with and with respect to said platform; andmeans to move said platform a predetermined distance toward said pressbed.

8. Apparatus as claimed in claim 5; said unloading station beingprovided with transfer means to deliver pallets to the return section ofa conveyor system, and with roller track means movable toward and awayfrom said press bed to receive each pallet and deposit it on saidtransfer means.

9. Apparatus as claimed in claim 8; said transfer means comprising apower driven belt traveling in part in a horizontal plane; said rollertrack means being movable to a position below said plane to release eachpallet to said belt.

10. A system for selectively returning formed workpieces to theiroriginal reload stations, comprising: a return section of a conveyorsystem having a receiving end at a forming press and a delivery enddefining an exchange zone, and provided with spaced rollers along itslength to transport workloads; a plurality of reload stations at saidexchange zone; an individual pallet for each reload station adapted tocarry form blocks with workpieces thereon; each pallet bearing an indexformation distinct from that of any other pallet; a diverter adjacent toeach reload station adapted to transfer a selected pallet from theconveyor section to the appropriate reload station; and detection meansadjacent to each reload station adapted to identify a selected pallet byits index formation and activate the diverter.

11. A system as claimed in claim 10; each pallet being in the form of adisk having a diameter substantially equal to the width of the conveyorsection to insure that the center of the disk will be on thelongitudinal center line of the conveyor at all points in its travel;each disk bearing in its bottom surface a concentric groove having aradius measurably different from the radius of the groove in any otherdisk; said detection means comprising a pair of switches and a pair ofvertically movable switch actuators adjacent to each reload station; afirst actuator of each pair being located laterally of the center lineof the conveyor a distance equal to the radius of the groove in theselected disk to be intercepted and at such height that it will closeits respective switch when it enters the groove in the selected disk;the second actuator of the pair being located on the center line of theconveyor and onward of the first actuator a distance equal to the radiusof the disk and at such height that it will close its respective switchwhen it is depressed by the leading edge of the disk; said switchesbeing connected to each other and to the diverter in series to causeactivation of the diverter only upon simultaneous closure of bothswitches.

12. A system as claim in claim 10; each diverter comprising a rollertrack assembly arranged between rollers of the conveyor and movablebetween a first, inoperative, position slightly below the plane of theconveyor rollers and a second, operative, position above said rollersand inclined toward its respective reload station; and power means toraise said assembly to said second position to lift a selected palletoff the conveyor rollers and transport it to said reload station; saidpower means being activated by its associated detection means.

References Cited UNITED STATES PATENTS 2,600,038 6/1952 Whale-y 2l4l1 X2,848,968 8/1956 Novak 72419 X 3,126,938 3/1964 McCoy 72419 X 3,149,7369/1964 Austin et a1 19885 X 3,184,030 5/1965 Ludwig 19885 X 3,250,3775/1966 Minichello et al 198-38 3,376,982 4/1968 Hutchinson 2141l MILTONS. MEHR, Primary Examiner.

US. Cl. X.R.

